Microstructure-based modeling of inner oxygen pressure in solid oxide electrolysis cells: Analysis of electrode delamination and mitigation

One of the major degradation mechanisms in the long-term operation of solid oxide electrolysis cells (SOECs) is the delamination of oxygen electrodes (OEs), driven by high inner oxygen pressure near the OE-electrolyte interface. However, the effects of transport properties and electrode thickness on the inner oxygen pressure are not well understood. This study employs a microstructure-based electrochemical model that accounts for electron and oxygen ion conduction, along with Butler-Volmer-type chemical reactions at triple-phaseboundaries (TPBs), to investigate the oxygen pressure in lanthanum strontium manganate (LSM)-based SOECs. The model is applied to both two-dimensional (2D) prototype microstructures and three-dimensional (3D) realistic microstructures, with the oxygen pressure evaluated as a function of transport properties and electrode thickness under both potentiostatic and galvanostatic operations. The simulation results suggest that electrode delamination can be mitigated by enhancing the ionic conductivities and thickness of the OE under potentiostatic operation, and by enhancing the ionic conductivities in the electrolyte and OE, as well as optimizing the thickness of OE under galvanostatic operation. The simulation results are compared to an analytical solution, with the discrepancies attributed to the Butler-Volmer-type kinetics included in the microstructure-based model.